Conventionally, an air conditioner including an indoor unit and an outdoor unit is known. When the air conditioner performs a heating operation in a state in which outdoor air temperature is low, there arises a frosted state in which frost forms on an heat exchanger of the outdoor unit. Since heat exchange efficiency of the heat exchanger of the outdoor unit is reduced in the frosted state, a defrosting operation for melting the frost on the heat exchanger of the outdoor unit is performed. However, in spite of the fact that the heating operation is performed, room temperature is decreased due to the defrosting operation.
For example, when an air conditioner described in PTL 1 finishes a defrosting operation and performs a heating operation, the air conditioner utilizes an amount of heat stored in a heat exchanger of an outdoor unit. Thus, the air conditioner stops driving of an outdoor fan until the temperature of the heat exchanger of the outdoor unit becomes lower than outdoor air temperature. Then, when the temperature of the heat exchanger of the outdoor unit becomes lower than the outdoor air temperature, the air conditioner accelerates rotation of the outdoor fan at the same acceleration as that used when it starts an operation such as the heating operation.